The serpin antithrombin III (AT III) is reported to have hemostasis-regulating and anti-inflammatory properties. To determine its ability to influence thrombin-independent leukocyte responses, the direct effects of the AT III concentrate Kybernin P and a monoclonal antibody-purified AT III on neutrophil migration were studied. Chemotactic activity of human neutrophils isolated from the blood of healthy donors was determined in modified Boyden microchemotaxis chambers, and binding studies were performed according to standard experimental protocols. Preincubation in vitro of neutrophils with Kybernin P or immune-adsorbed AT III significantly deactivated migration toward fMet-Leu-Phe, or interleukin-8 (IL-8), in a concentration-dependent manner. In the absence of additional attractants, neutrophils exhibited a migratory response toward gradients of AT III preparations. True chemotaxis was confirmed in checkerboard assays. Analyses revealed that the AT III heparin-binding site interacts with neutrophil membrane-associated heparan sulfate proteoglycan receptors. Mechanisms of intracellular signaling differed; the deactivation of IL-8-induced chemotaxis resulted from tyrphostin-sensitive interactions of AT III-signaling with the IL-8 signal transduction pathway, whereas AT III-induced chemotaxis involved protein kinase C and phosphodiesterases. Signaling similarities between AT III and the proteoglycan syndecan-4 may suggest the binding of AT III to this novel type of membrane receptor. Under physiological conditions, AT III may prevent neutrophils from premature activation. Moreover, the systemic administration of AT III concentrate could have beneficial effects in combating systemic inflammation.
As the ability of antithrombin to deactivate neutrophil chemotaxis toward interleukin 8 shows differences depending on the source of commercial antithrombin, these results suggest that at equivalent WHO standard concentrations clinical antithrombin concentrates may differ in anti-inflammatory potential.
Aims: To study the relationship between myocardial release of cTnI and myocardial cell death as assessed by the amount of apoptosis and necrosis after cardiac surgery. Methods: Eighteen young pigs were operated on with standardized cardiopulmonary bypass (CPB). Release of cTnI in the cardiac lymph (CL), coronary sinus (CS), and arterial blood (A) was related to postoperative myocardial cell death by both necrosis and apoptosis. Apoptotic cells were detected by a TUNEL detection kit. Necrotic cells were counted by light microscopy. Results: In all animals, cTnI was significantly released and reached peak values observed simultaneously in A (cTnI, 20.1±2.6 ng/ml) (mean ±SEM), CS (19.5±3.2 ng/ml) and CL (5202±2500 ng/ml). Percentage of total myocardial cell death was 3.1±0.5%, including 1.2±0.35% necrosis and 1.9±0.5% apoptosis. cTnI release during and after CPB did not correlate with the degree of myocardial apoptosis or necrosis. Conclusion: Cardiac operations with CPB are related to myocardial cell damage including myocardial cell death due to both necrosis and apoptosis. As the loss of cTnI is not related to the amount of cell death, our results suggest that increased cardiac myocyte membrane permeability more than cell death is responsible for intraoperative and postoperative cTnI release.
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